McGill climate

McGill Frost Dates and Growing Season

NOAA 1991-2020 normals for Mcgill, 1.1 km from McGill, elevation 6270 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mcgill. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around May 28 and the first fall freeze around September 24, a growing season of about 119 days.

Median at 36°F
last June 9, first September 16
Median at 32°F
last May 28, first September 24
Median at 28°F
last May 11, first October 4

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FJun 27Jun 20Jun 16Jun 12Jun 9Jun 6Jun 3May 31May 24
32°FJun 13Jun 7Jun 4May 31May 28May 24May 21May 15May 10
28°FJun 2May 24May 19May 15May 11May 8May 4Apr 30Apr 25
24°FMay 15May 7May 3Apr 30Apr 26Apr 23Apr 19Apr 14Apr 8
20°FMay 1Apr 24Apr 18Apr 13Apr 10Apr 7Apr 4Mar 31Mar 23
16°FApr 12Apr 6Apr 1Mar 29Mar 24Mar 19Mar 14Mar 9Mar 4

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FSep 2Sep 7Sep 10Sep 13Sep 16Sep 18Sep 21Sep 23Sep 26
32°FSep 11Sep 16Sep 20Sep 22Sep 24Sep 27Sep 29Oct 1Oct 6
28°FSep 22Sep 26Sep 29Oct 1Oct 4Oct 7Oct 10Oct 14Oct 17
24°FOct 1Oct 4Oct 8Oct 11Oct 14Oct 16Oct 19Oct 23Oct 28
20°FOct 8Oct 13Oct 17Oct 20Oct 24Oct 27Oct 30Nov 2Nov 7
16°FOct 18Oct 24Oct 29Nov 1Nov 4Nov 6Nov 11Nov 16Nov 21

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F1141081041009693898476
32°F14013412812311911411010598
28°F168160155150147143138131122
24°F191184179175171166162156149
20°F220211205200196191186180171
16°F249241234229224219213206198

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
6,754
Cooling degree days, base 65°F
454
Growing degree days, base 40°F
4,248
Growing degree days, base 45°F
3,169
Growing degree days, base 50°F
2,269
Growing degree days, base 55°F
1,526
Growing degree days, base 60°F
921

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,14500
February95500
March81907
April611036
May3786161
June12163399
July11195649
August15163614
September16927322
October524174
November85107
December1,15600

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 1.1 km from McGill. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00264950 (Mcgill). Public domain.